Eight nuclear power companies in Japan, including Tokyo Electric Power (TEPCO), Hokkaido Power Company, and Tohoku Electric admitted that they have been the targets of recent cyber attacks. All said that no data was leaked from their data systems. However, the attacks are raising concern about vulnerability to terrorist attacks.

The Nuclear and Industrial Safety Agency (NISA) said it agrees with TEPCO that last week’s discovery of xenon-135 in Reactor 2 indicated spontaneous fission rather than sustained fission, which could have led to criticality. The agency based its assessment on the fact that injecting boric acid had no effect on the density of xenon in the reactor. However, experts have raised concern about TEPCO’s ability to accurately assess the state of the reactors after the utility initially announced that criticality might be taking place. Because radiation levels remain dangerously high, workers have been unable to install monitoring equipment to appraise the current conditions inside the reactors. Instead, the company is relying on computer simulations based on temperature and pressure levels.

TEPCO workers discovered radiation measured 620 millisieverts per hour in Reactor 3 of the Fukushima Daiichi plant this week — the highest levels measured since the March disaster occurred. The World Nuclear Association recommends that workers avoid short-term exposure greater than 500 millisieverts per hour, and then only in life-saving situations.

The former President of India, Abdul Kalam, is insisting that a planned nuclear plant poses no danger, at the same time that local villagers, who fear a disaster similar to that of Fukushima, continue to protest. Meanwhile, the former governor of West Bengal, Gopal Krishna Gandhi, has taken the opposite view, expressing concerns about safety. Gandhi, who is the grandson of Mahatma Gandhi, expressed concern about seismic dangers and terrorist attacks, warning that there have been over 20 earthquakes in India over the last six weeks.